I need help to fix an issue on a PHP Library

General information for the website: Appizy converts OpenDocument Spreadsheet into Web-calculators

Hello,

I am the developer of the project Appizy (homepage: http://www.appizy.com, Github: https://github.com/Appizy/appizy).

I look for a PHP developer to fix this issue: https://github.com/Appizy/appizy/issues/15

Description of requirements/features: Please read the following page to understand the concept of the library: https://github.com/Appizy/appizy/blob/master/CONTRIBUTING.md

You need to be at ease with:
- PHP 5.6 and 7.*
- OOP
- PHPUnit
- Docker (no setup required just using it)
- Excel/OpenDocument Spreadsheet (good knowledge)
- Linux base commands

You need a Github account (please provide your Github ID in your application).

Reply to this job only if you achieved to clone the repo on your machine and run the unit tests in Docker.